Refill for electric toothbrush

ABSTRACT

A refill for an electric toothbrush comprises a generally tubular structure formed by refill walls defining an interior space for accepting thereinto a coupling stem of a toothbrush handle. The refill includes a motion transmitter functionally connected to the brush head for driving it. The refill has a coupling device including a pair of mutually opposite and resiliently deformable cantilevered arms disposed in the interior space of the refill and adjacent to the refill walls and extending from respective roots in a circular or semi-circular manner around, and in a plane substantially perpendicular to, the refill&#39;s longitudinal axis. Each of the arms is resiliently deformable and terminates with a coupling surface for engaging a coupling pin extending from the handle&#39;s coupling stem for secure and disengageable connection therewith.

RELATED APPLICATION INFORMATION

This application claims priority to provisional application Ser. No.62/525,657, filed on Jun. 27, 2017, which provisional application isincorporated herein by reference.

FIELD OF THE INVENTION

The present disclosure is directed to an electric toothbrush, and moreparticularly to a coupling arrangement between the toothbrush's handleand an attachment part, or refill, wherein the refill having afunctional brush head is connected to a toothbrush handle comprising adrive shaft for driving the brush head.

BACKGROUND

Electric toothbrushes generally have removable and exchangeableattachment brushes, also known as “refills,” so that a common handle canbe used by multiple family members, each family member having a separatepersonal refill. Also, when the brush head is worn out and/or otherwiseneeds to be replaced, only a refill—as opposed to the entire electrictoothbrush including the handle—needs to be replaced.

During brushing, various forces must be transmitted by the couplingbetween the refill and the handle during operation of the brush. Theseforces include in particular the cleaning forces, drive forces, axialforces, and radial forces, which act on the refill and/or the handle.The coupling of the refill to the handle is generally achieved in such away that the radial forces are absorbed or dissipated in the handle,while the axial forces are absorbed or dissipated in the drive shaft.For this purpose, the tubular connecting piece of the refill isgenerally pushed onto the coupling stem, or neck, of the toothbrush, andthe drive shaft, provided in the brush tube of the refill, is coupled tothe drive shaft that protrudes from the end of the handle's couplingstem.

An example of such a system is described in EP 0500537 B1, according towhich the handle neck, and, in a correspondingly complementary fashion,the tubular connecting piece, are provided with a cross-section thatdeviates from a circular shape to enable radial forces to be betterabsorbed. In order to enable transmission of the axial forces, the driveshaft in the brush tube can be pushed onto the drive shaft on the handleand secured there by a latching connection.

WO 00/76420A1 proposes that the axial fixing and also the fixing againstrotation be achieved at the handle neck. For these purposes,saw-tooth-shaped rubber lips are provided in the tubular connectingpiece of the attachment brush, which lips can be pushed onto the handleneck, the shape of which deviates from a circular shape. In addition,latching tongues are provided on the tubular connecting piece that canbe pushed over the outer circumferential surface of the handle neck andcan be latched there; this is intended to achieve additional securingagainst a pulling off in the axial direction. However, the additionalaxial securing achieved by this latching device is limited due to theouter circumference of the handle neck becoming dirty, for example withtoothpaste residue and the like. In addition, the neck of the toothbrushis sometimes grasped with the fingers, which can cause unintentionaldisengagement due to external pressure on the latching connection.

U.S. Pat. No. 6,836,917 proposes an electric toothbrush that has anL-shaped groove on the neck of the toothbrush, into which a pin providedon the push-on connecting piece of the attachment brush moves, such thatthe attachment brush can be secured by pushing it on and rotating it, inthe style of a bayonet coupling. In addition, provision is made for anengaging of the drive shafts. However, radial forces can causeunintentional disengagement of the bayonet coupling if these forces areapplied in the correct (so to speak) direction of rotation relative tothe handle, thus making additional securing measures necessary.

DE 10209320A1 discloses an electric toothbrush in which only atoothbrush head can be exchangeably latched to the handle; i.e., thetoothbrush head does not have a drive shaft for driving same. Instead, adrive shaft on the handle must be threaded into the toothbrush head,which can sometimes pose problems and requires a particular drivemovement of the drive shaft.

U.S. Pat. No. 8,671,492 discloses an attachment part for an electrictoothbrush wherein the connecting piece has at least one interiorlatching element arranged to move into the interior of the neck of thehandle and to create a disengageable connection of the attachment partto the neck of the handle. The interior latching element is radiallyinwardly offset, with regard to the diameter thereof, relative to aninternal cylindrical surface of the connecting piece. A gap between theexterior of the interior latching element and the internal cylindricalsurface allows a wall of the neck of the handle to be moved into it.

US 2014/0130274A1 discloses a structure for coupling the refill head toa toothbrush handle that ensures proper alignment and simplifies theloading and unloading of the refill head to the handle. In oneembodiment, the refill head comprises a tubular sleeve forming a cavityand first and second upper cam surfaces that form shoulders within thecavity. The first and second upper cam surfaces are separated by firstand second axial slots of different configurations that prevent loadingof the refill head onto the oral care implement handle in an improperrotational orientation through interaction with first and second bosseson the oral care implement handle.

US 2014/0341636A1 (EP2913026A1) discloses a refill head (100), and oralcare implement incorporating the same, wherein the refill head (100) canbe uncoupled from a stem (220) of a handle (200) by withdrawing therefill head (100) from the stem of a handle (200) along the longitudinalaxis of the oral care implement, which results in locking members (134)on the refill head (100) disengaging from an engagement rib (230) on thestem (220). The locking members (134) and engagement rib (230) may bealigned with or angled relative to the longitudinal axis of the oralcare implement. A portion of the stem may be visible through a portionof the refill head to reinforce the proper connection between the refillhead and the handle.

Other references disclosing various techniques for and ways of couplingthe refill to the handle of an electric toothbrush include: U.S. Pat.No. 4,017,934; DE2527130A1; DE2633848A1; U.S. Pat. Nos. 6,952,855;3,400,417; and 9,237,943.

The present disclosure provides a further improved electric toothbrush,an improved refill, an improved handle; and an improved handle-refillcoupling mechanism for such an electric toothbrush, wherein aneasy-to-operate coupling is formed between the refill and the handlethat holds the refill firmly and with as little play as possible on thehandle, and still permits an easy coupling, including engagement anddisengagement, between the handle and the refill.

SUMMARY OF THE DISCLOSURE

In one aspect, the disclosure is directed to an electric toothbrushhaving a longitudinal direction or axis and comprising a handle and arefill structured and configured to be attached to the handle via acoupling device. The handle has a drive mechanism, and the refill has abrush head and a motion transmitter functionally connected to the brushhead for driving the brush head. The handle further comprises a couplingstem having outer walls extending in a direction parallel to thelongitudinal axis and terminating with a free end; and the coupling stemhas a coupling pin extending therefrom in a direction not parallel tothe longitudinal axis. The refill has a generally tubular portion formedby refill walls defining an interior space, which is structured andconfigured to accept therein the coupling stem of the handle when therefill is attached to the handle. The coupling device comprises a pairof mutually opposite cantilevered arms disposed in the interior space ofthe refill and adjacent to the refill walls, each of the armsterminating with a coupling surface structured and configured to engagethe coupling pin for secure and disengageable connection therewith.

In another aspect, the disclosure is directed to a refill for anelectric toothbrush having a longitudinal axis. The refill, structuredand configured to be attached to a handle of the electrical toothbrush,has a movable brush head and comprises a generally tubular structureformed by refill walls defining an interior space that is structured andconfigured to accept therein a coupling stem of the handle. The refillincludes a motions transmitter functionally connected to the brush headfor driving the brush head. The refill includes a coupling devicecomprising a pair of mutually opposite cantilevered arms disposed in theinterior space of the refill and adjacent to the refill walls, each ofthe arms terminating with a coupling surface structured and configuredto engage a coupling pin extending from the coupling stem of the handlefor secure and disengageable connection therewith.

In still another aspect, the disclosure is directed to a couplingmechanism for an electric toothbrush having a longitudinal axis andcomprising a handle and a replaceable refill. The coupling mechanismcomprises a handle coupling portion and a refill coupling portion thatare structured and configured to engage one another, thereby providing asecure connection between the handle and the refill. The handle couplingportion comprises a coupling stem disposed at one end of the handle inthe longitudinal axis and a pin protruding from the stem in a directionnot parallel to the longitudinal axis, the coupling stem having outerwalls terminating at a free end thereof. The refill coupling portioncomprises a generally tubular structure having refill walls and aninterior space therebetween structured and configured to receive thereinthe coupling stem of the handle coupling portion, and a pair of mutuallyopposite cantilevered arms disposed in the interior space, each of thearms terminating with a coupling surface structured and configured toengage the coupling pin of the handle coupling portion for secure anddisengageable connection therewith.

In one embodiment, the coupling pin extends in a direction substantiallyperpendicular to the longitudinal axis and/or a direction substantiallyperpendicular to the outer walls of the coupling stem. The coupling stemmay beneficially include a rib oriented in the longitudinal axis andhaving a first (lower) end and a second (upper) end opposite to thefirst end. The rib can be disposed adjacent to the pin. In oneembodiment, the pin is disposed between or intermediate the first endand the second end of the rib. The refill may comprise a groovestructured and configured to engage the upper end of the rib of thecoupling stem, to restrict axial movement of the refill relative to thehandle when the refill is being axially attached to the handle.

Each of the two mutually opposite cantilevered arms terminates with acoupling surface. More specifically, a first cantilevered arm terminateswith a first coupling surface and a second cantilevered arm terminateswith a second coupling surface. The first coupling surface is oppositeto and faces the first coupling surface. The first and second couplingsurfaces are structured and configured to simultaneously embrace thecoupling pin at opposite sides thereof when the refill is attached tothe handle. Each of the coupling surfaces comprises a slide portion anda clamp portion adjacent to the slide portion. A distance between themutually opposite slide portions of the first and second couplingsurfaces can be from about 0.4 mm to about 5 mm, from about 0.5 mm toabout 4.5 mm, from about 0.6 mm to about 3 mm, and specifically fromabout 1 mm to about 2 mm. The pin's diameter (or an equivalent dimensionorthogonal to the slide portions if the pin is not cylindrical) can befrom about 0.8 mm to about 6 mm, from about 1 mm to about 5 mm, and fromabout 2 mm to about 4 mm. The pin may have a cross-section of anysuitable shape, including, e.g., a shape comprising round, oval,rectangular, trapezoidal, rectangular, pentagonal, hexagonal, and anyother suitable polygonal shape or any portion thereof.

The coupling surfaces are structured and configured to slidably andresiliently engage the coupling pin when the refill is being axiallyattached to the handle, i.e., when the refill is being axially movedrelative to the handle and the pin arranged thereon. During attachment,the mutually opposite slide portions of the coupling surfaces slidedownwardly in resilient contact with the pin. When the pin reaches theclamp portion, the pin is pulled into a snap fit with the couplingsurfaces inside the clamp portion. To facilitate the pin's entry intothe space between the two coupling surfaces, each of the slide portionsmay include a chamfer.

The slide portions of the first and second coupling surfaces can bearranged substantially parallel to the longitudinal axis (and henceparallel to one another). Alternatively, at least one of slide portionscan be angled relative to the longitudinal axis. An included anglebetween the slide portions can be from about 0.1 degree to about 20degrees, from about 1 degree to about 15 degrees, from about 1.5 degreesto about 10 degrees, and specifically from about 2 degrees to about 3degrees. In one embodiment, each of the slide portions are symmetricallyangled relative to the longitudinal axis such that the space between themutually opposite slide surfaces increases upwardly, i.e., from thechamfers to the clamp portion. Such a configuration facilitates pullingof the pin into the clamp portion of the coupling surfaces, due to theresilience of the cantilevered arms and associated pressure of thecoupling surfaces acting on the pin as the pin slides along the slidesurfaces.

As the refill is being attached to the handle, a space or clearanceexisting between the two mutually opposite coupling surfaces of thecantilevered arms resiliently expands—as the pin slides along theopposite slide portions of the coupling surfaces. When this happens, theelastic (or resilient) deformation or movement of the cantilevered armsmay include a radial-bending elastic deformation, i.e., a resilientmovement of the arms away from the toothbrush's longitudinal axis; anaxial-bending elastic deformation, i.e., a resilient movement of thearms along the toothbrush's longitudinal axis; a torsion-twistingelastic deformation, i.e., a resilient torque movement of thecantilevered arm wherein the coupling surface rotates relative to thearm's portion adjacent to its “hinge” or “root” (from which the armextends); and any combination thereof.

Because of repeated attachments of the refill to and dis-attachments ofthe refill from the handle, there is an inevitable wear at the interfaceof the pin and coupling surfaces, particularly in an environmentcontaining abrasive material such as toothpaste slurry. It is thereforebeneficial to have the pin (which is part of the handle) made of amaterial having a hard surface, such, e.g., as steel, ceramics,reinforced plastic, as well as hard-surface-coated materials. Thecoupling surfaces (which are part of the refill) can be made of plastic.Such an arrangement beneficially meets the requirements of functionalityover respective expected lifetimes of the handle and the refill.

The pin may have any suitable shape, e.g., cylindrical or prismatic,although the cylindrical shape is preferred. Correspondingly, the clampportions of the coupling surfaces can also be profiled to have acircular or semi-circular shape, wherein a diameter of the pin issubstantially equal to an equivalent diameter of the clamp portion. Insuch an arrangement, the entire surface of the clamp portion is incontact with the side surface of the coupling pin. In one exemplaryembodiment, the clamp portion of each of the first and second couplingsurfaces is structured and configured to abut a side surface of thecoupling pin such that substantially an entire surface of the clampportion is in contact with the side surface of the coupling pin. Inother words, the respective surfaces of the pin and the clamp portionscan be structured and configured such that virtually the entire clampportion of each of the coupling surfaces (or its major portion, that ismore than about 50% of the relevant surface) is in contact with thecorresponding surface of the pin. In another embodiment, the pin may becylindrical, but the coupling surface may be non-cylindrical, e.g., ovalor polygonal. In the latter instance, the contact surfaces of the clampportion will only partially abut the cylindrical pin. The couplingsurfaces, including the clamp surfaces, can be configured to influenceand/or control the insertion and extraction forces needed to be appliedwhen the refill is being attached to the handle.

The refill, and the coupling mechanism, can be structured to comprise acoupling insert disposed inside the tubular portion of the refill andfit-pressed thereto. The insert has a front portion comprising an uppersection, a lower section, and a middle section between the upper andlower sections, wherein the lower section is separated from the middlesection by a first semi-circular space and the middle section isseparated from the upper section by a second semi-circular space. Thelower section may comprise an annular flange extending in a directionsubstantially perpendicular to the longitudinal axis and comprising aninner perimeter and an outer perimeter. When the refill is attached tothe handle, the annular flange can be positioned adjacent to the handle.The inner perimeter of the flange may beneficially include a recessstructured and configured to provide a space for the rib of the couplingstem when the refill is being attached to the handle.

The middle section comprises the pair of mutually opposite cantileveredarms, previously described. The cantilevered arms are positioned suchthat they can resiliently move, as previously described, relative to thelower section and the upper section. The upper section may include thegroove, previously described, for engaging the upper end of the riblongitudinally extending from the coupling stem, to restrict axialmovement of the refill relative to the handle when the refill is beingaxially attached to the handle.

In one embodiment, the outer walls of the coupling stem and the refillwalls form, in combination, a plurality of press-fit segments whereinopposite faces thereof frictionally engage one another when the refillis attached to the handle. The press-fit areas can be provided at anysuitable location, e.g., adjacent to the free end of the coupling stemand/or adjacent to an end opposite to the free end of the coupling stem.Each of the press-fit areas can have at least two press-fit segments,i.e., points of frictional contact. In one embodiment, the plurality ofpress-fit segments comprises three press-fit adjacent to the free end ofthe coupling stem and at least three press-fit segments adjacent to theend opposite to the free end of the coupling stem.

In one embodiment, the coupling insert comprises at least onetolerance-compensation spring extending upright in a general directionsubstantially parallel to the longitudinal axis and having a free end.The tolerance-compensation spring can be structured and configured sothat when the refill is attached to the handle, at least a portion ofthe tolerance-compensation spring adjacent to its free end resilientlybiases the insert against the surface of the coupling stem, therebyproviding a frictional connection therebetween.

In a further embodiment, each of the cantilevered arms may comprise acurved portion and a vertical fin integrally formed with the curvedportion, wherein the fin includes the coupling surface, previouslydescribed. The curved portion has a curvature length measured in acircumferential direction, a curvature height measured in a directiongenerally perpendicular to the curvature length, and a curvaturethickness measured in a direction generally perpendicular to thecurvature height. In one embodiment, the curvature length is greaterthan the curvature height and the curvature height is greater than thecurvature thickness. In one embodiment, the vertical fin has a finheight that is greater than the curvature height. The curvature lengthcan be from about 4 mm to about 10 mm, from about 4.5 mm to about 9 mm,and from about 5 mm to about 8 mm. The curvature height can be fromabout 2 mm to about 8 mm, from about 2.5 mm to about 6.5 mm, and fromabout 3 to about 5 mm. The curvature thickness can be from about 0.5 mmto about 2 mm, from about 0.7 mm to about 1.8 mm, and from about 0.9 mmto about 1.6 mm. The fin height can be from about 3 mm to about 12 mm,from about 5 mm to about 10 mm, and from about 6 mm to about 9 mm.

In one embodiment of the toothbrush and the refill, the refill may havea motion transmitter that terminates with a first magnetic couplingelement, while the drive mechanism of the handle terminates with asecond magnetic coupling element. Then, the first magnetic couplingelement and the second magnetic coupling element can be structured andconfigured to form a secure magnetic connection therebetween when therefill is attached to the handle, so that the movement of the handle'sdrive mechanism is transmitted to the refill's motion transmitter. Suchmagnetic coupling elements may include permanent magnet or magnetsand/or a magnetizable element or elements.

The drive mechanism of the handle can be designed for a linearoscillatory movement substantially along the longitudinal axis A, whilethe brush head can be designed for a rotational oscillatory motionaround a rotation axis extending substantially perpendicular to thelongitudinal axis A. Alternatively or additionally, the brush head canbe designed to move in a lateral oscillatory motion around an axisextending substantially parallel to the longitudinal axis A, or anyother type of movement, such as, e.g., a linear oscillatory movement, avibratory action, and/or other movement patterns, as is known in theart.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments set forth in the drawings are schematic and illustrativein nature, and not intended to limit the invention defined by theclaims. The following detailed description of the illustrativeembodiments can be better understood when read in conjunction with thefollowing drawings, in which like structures are indicated with likereference numerals.

FIG. 1 is a schematic axonometric view of an embodiment of an electrictoothbrush.

FIG. 2 is a schematic axonometric view of a refill of the toothbrushshown on FIG. 1.

FIG. 3 is a schematic axonometric view of a handle of the toothbrushshown on FIG. 1.

FIG. 4 is a schematic front view of an embodiment of a coupling deviceof the disclosure.

FIG. 5 is a schematic axonometric view of an embodiment of a couplingdevice shown in FIG. 4.

FIG. 6 is a schematic axonometric view of a coupling insert shown aspart of the coupling device in FIG. 4.

FIG. 7 is a schematic front view of a fragment of a toothbrush includingthe coupling device of the disclosure, showing a motion transmitter witha magnetic element for connecting the motion transmitter to acorresponding magnetic element of the handle.

FIG. 8 is an enlarged schematic front view of an embodiment of thecoupling insert shown in FIG. 6.

FIG. 8A is a schematic cross-sectional view, taken along lines 8A-8A, ofthe coupling insert shown in FIG. 8.

FIG. 9 is an enlarged schematic front view of an embodiment of acoupling device shown in

FIG. 4.

FIG. 9A is an enlarged fragmental view of another embodiment of acoupling device.

FIG. 10 is a schematic axonometric view of an embodiment of the couplingdevice, showing press-fit segments for connecting the stem to thehandle.

FIG. 11 is another schematic axonometric view of an embodiment of thecoupling device, showing press-fit segments for connecting the stem tothe handle.

FIG. 12 is a schematic view of an embodiment of a refill, without itsouter shell, and a portion of a handle, showing a motion transmitter andmagnetic coupling elements.

FIG. 13 is a schematic axonometric view of an embodiment of a couplinginsert having a tolerance-compensation spring.

FIG. 14 is a schematic cross-sectional side view of an embodiment of acoupling device, including the coupling insert having atolerance-compensation spring resiliently abutting the coupling stem ofa handle.

DETAILED DESCRIPTION

As is shown in FIGS. 1-3, an electric toothbrush 10 of the disclosurecomprises a handle 20 and a refill 30 having a longitudinal axis orlongitudinal direction A. In the embodiment of FIG. 1 the longitudinalaxis A of the refill 30 coincides with that of the handle 20, but oneskilled in the art will appreciate that in some embodiments (not shownhere) the refill can be designed to be slightly angled relative to thehandle, in which instances the longitudinal axis of the refill may notcoincide with or be parallel to the that of the handle. Such an angledembodiment is included in the scope of the invention.

The refill 30 is structured and configured to be attached to the handle20 via a coupling device 100, FIGS. 4-7. The handle 20 has a drivemechanism (not shown) inside, and the refill 30 has a brush head 31 anda motion transmitter 300 (FIG. 7) functionally connected to the brushhead 31 for driving the brush head 31. The handle 20 further comprises acoupling stem 200 having outer walls 210 extending in the longitudinalaxis A and terminating with a free end 220. The coupling stem 200 has acoupling pin 230 extending therefrom in a direction not parallel to thelongitudinal axis A. Preferably, the coupling pin 230 extends from thecoupling wall 210 at an approximately right angle, or substantiallyperpendicular relative to the longitudinal axis A.

The coupling stem 200 may beneficially include a coupling rib 240outwardly (or radially) protruding from the stem 200 and longitudinallyoriented in a direction generally parallel to the longitudinal axis A.The rib 240 has a first (lower in the figures) end 241 and a second(upper) end 242 opposite to the first end 241. The rib 240 can bedisposed adjacent to the pin 230. In the embodiment of FIGS. 4 and 5,the coupling pin 230 is disposed between or intermediate the first end241 and the second end 242 of the rib 240. The rib 240 and the couplingpin 230 may be constructed to outwardly protrude from the stem 200 tothe same extent, i.e., an outmost outer surface of the rib 240 can beflush with an outmost outer surface (free end) of the coupling pin 230.Alternatively, the coupling pin 230 can protrude from the coupling stem200 to a greater extent that the rib 240 does, in which instance aportion of the coupling pin 230 extends beyond the outmost outer surfaceof the rib 240 (FIGS. 4, 5).

The refill 30 may comprise a groove 128 structured and configured toengage the second end 242 of the rib 240, to restrict a movement (axialand/or radial) of the refill 30 relative to the handle 20 when therefill 30 is being axially attached to the handle 20. The groove 128 canbe beneficially sized and shaped to match the size and shape of thesecond end 242 of the rib 240. In an embodiment of FIGS. 4 and 5, thesecond end 242 of the rib 240 is shown to have a convex, generallysemi-circular shape; and the grove 128 is shown to have a correspondingconcave, generally semi-circular shape. Other mutually correspondingshapes of the rib 240 and the groove 128 are contemplated by thedisclosure. Also, the second end 242 of the rib 240 can have othersuitable configurations, which may or may not have to transition in atangential manner.

The refill 30 has a generally tubular portion 33 formed by refill walls34. The tubular portion 33 can have any suitable shape, including, e.g.,a generally cylindrical shape, a generally conical shape, or anycombination thereof. As used herein, the terms “generally cylindrical”and “generally conical” describe shapes strictly cylindrical and conicaland those deviating from strictly cylindrical and conical shapes.Examples of such “generally cylindrical” and “generally conical” tubularportion 33 include, without limitation, the tubular portion 33 having across-sectional shape deviating from circular by being elongated in onedirection, e.g., elliptical, oval, and the like. The tubular portion canhave other suitable shapes as well, e.g., polygonal, rectangular, and soon—or a combination of generally cylindrical/conical and polygonalshapes. Inside the tubular portion 33, there is an interior space,defined by the refill's walls 34 and structured and configured to accepttherein the coupling stem 200 of the handle 20 when the refill 30 isattached to the handle 20. The coupling device 100 comprises a pair ofmutually opposite cantilevered arms 150 disposed in the interior spaceof the refill 30 and adjacent to the refill walls 34, and morespecifically adjacent to the interior surfaces of the refill walls 34.The cantilevered arms 150 are curved and can be described as generallycircular or semi-circular, which means that a cross-sectional shape ofthe arms 150, taken in a plane substantially perpendicular to thelongitudinal axis A, can comprise portions that are circular or cancomprise portions that deviate from an ideal circular shape—similarly tothe deviation of the previously described generally cylindrical andgenerally conical tubular portion 33, i.e., by being elongated in onedirection, to comprise, e.g., a portion of an elliptical, oval, and thelike shape.

A pair of the curved cantilevered arms 150 comprises a first arm 150 aand a second arm 150 b opposite to the first arm 150 a. Each of thecantilevered arms 150 has its fixed end (or “root”) 151 (151 a, 151 b)and terminates with a free end 152 (152 a, 152 b). The free end 152includes a coupling surface 153 (153 a, 153 b) structured and configuredto engage the coupling pin 230 of the coupling stem 200 for secure anddisengageable connection therewith. In a coupling mechanism of thedisclosure, the coupling pin 230 forms a handle coupling portion, andthe coupling device 100 forms a refill coupling portion. As can be seenin FIGS. 8, 9, and 9A, the cantilevered arms 150 extend from the root151 in a generally circular or semi-circular manner and in a planesubstantially perpendicular to the longitudinal axis A. In other words,the cantilevered arms 150 curve around the longitudinal axis A in aplane substantially perpendicular to the axis A. In the embodimentshown, the roots 151, the cantilever arms 150, and the coupling surfaces153 (and the coupling pin 230 when the refill 30 is properly attached tothe handle) are disposed in a general plane that is substantiallyperpendicular to the longitudinal axis A.

A first cantilevered arm 150 a terminates with a first coupling surface153 a, and a second cantilevered arm 150 b terminates with a secondcoupling surface 153 b. The first coupling surface 153 a is opposite toand faces the second coupling surface 153 b. The first and secondcoupling surfaces 153 a, 153 b are structured and configured tosimultaneously embrace the coupling pin 230 at its opposite sides whenthe refill 30 is being attached to the handle 20.

Each of the first and second coupling surfaces 153 a, 153 b comprises aslide portion 154 (154 a, 154 b) and a clamp portion 155 (155 a, 155 b)adjacent to the slide portion 154. A distance between mutually oppositea first slide portion 154 a and a second slide portion 154 b, of thefirst and second coupling surfaces 153 a, 153 b, respectively, can befrom about 0.4 mm to about 5 mm, from about 0.5 mm to about 4.5 mm, andfrom about 0.6 mm to about 3 mm. In one particular embodiment, thedistance between the two mutually opposite first slide portion 154 a andsecond slide portion 154 b is between about 1 mm and about 2 mm. Thisdistance can be measured as an average of a maximal distance D1 and aminimal distance D2, as is shown in FIG. 8, when the refill 30, havingthe coupling device 100 therein, is not attached to the handle 20, i.e.,when the coupling device 100 is not experiencing elastic deformation, asdescribed herein.

In embodiments in which the coupling pin 230 is generally cylindrical, adiameter of the pin 230 (or an equivalent dimension orthogonal to theslide portions if the pin is not cylindrical) can be from about 0.8 mmto about 6 mm, from about 1 mm to about 5 mm, and from about 2 mm toabout 4 mm. The mutually opposite clamp portions 155 a, 155 b of thecoupling surfaces 153 a, 153 b, respectively, can beneficially match, inshape and size, the outer surface of the coupling pin 230.

The coupling surfaces 153 are structured and configured to slidably—andresiliently by virtue of resiliency of the cantilever arms 150—engagethe coupling pin 230 when the refill 30 is being axially attached to thehandle 20, i.e., when the refill 30 is being axially moved relative tothe handle 20 and the coupling stem 200 having the coupling pin 230arranged thereon. During the axial attachment, the coupling pin 230contacts the mutually opposite slide portions 154 of the couplingsurfaces 153 at the pin's opposite sides as the pin 230 slides upwardly,in a resilient contact with the slide portions 154. When the pin 230reaches the clamp portion 155, the pin 230 is pulled into a snap fitwith the clamp portions 155 a, 155 b. To conveniently position the pin230 relative to the mutually opposite coupling surfaces 153 and tofacilitate the pin's entry into the space between the two couplingsurfaces 153, each of the slide portions 154 may include a chamfer 156.An angle α2 formed between a surface of the chamfer 156 and the slideportion 154 can be, e.g., from about 100 degrees and 170 degrees, fromabout 110 degrees and about 160 degrees, and from about 120 to about 150degrees.

At least one of the slide portions 154 can be angled relative to thelongitudinal axis A. In the embodiments shown in FIGS. 4 and 8, bothslide portions 154 are symmetrically angled relative to the longitudinalaxis A such that the space between the mutually opposite slide surfaces154 increases upwardly, i.e., the space between the first slide portion154 a and the second slide portion 154 b increases in the direction fromthe chamfers 156 to the clamp portion 155. Such a configurationfacilitates pulling of the pin 230 into the clamp portion 155 of thecoupling surfaces 153, due to the resilience of the cantilevered arms150 and an associated pressure of the coupling surfaces 153 acting onthe coupling pin 230 as the pin 230 slides along the slide portions 154towards the clamp portion 155. An included angle α1 formed between thetwo opposite slide portions 154 a, 154 b of the cantilevered arms 150can be from about 0.1 degree to about 20 degrees, from about 1 degreesto about 15 degrees, and from about 1.5 degrees to about 10 degrees. Inone particular embodiment, the angle α1 is from about 2 degrees to about3 degrees. In another embodiment, the slide portions 154 of the firstand second coupling surfaces 153 can be arranged substantially parallelto the longitudinal axis A, and hence substantially parallel to oneanother, FIG. 9 (showing a distance D3 between the two slide portions154 a, 154 b).

An alternative embodiment (not shown), in which the slide portions 154are oppositely angled relative to the longitudinal axis A, wherein thespace between the two slide surfaces 154 a, 154 b decreases upwardly,i.e., the space between the first slide portion 154 a and the secondslide portion 154 b decreases in the direction from the chamfers 156 tothe clamp portion 155, is also contemplated in the present invention.

When the refill 30 is being attached to the handle, a space or clearanceexisting between the two mutually opposite coupling surfaces 153 of thecantilevered arms 150 resiliently expands—as the coupling pin 230 slidesalong the opposite slide portions 154 of the coupling surfaces 153. Whenthis happens, the elastic (or resilient) deformation or movement of thecantilevered arms 150 may include a radial-bending elastic deformation,i.e., a resilient movement of the arms 150 away from the toothbrush'slongitudinal axis A; an axial-bending elastic deformation, i.e., aresilient movement of the arms 150 along the toothbrush's longitudinalaxis A; a torsion-twisting elastic deformation, i.e., a resilient torquemovement of the cantilevered arm 150 wherein the coupling surface 153rotates relative to the arm's fixed end or “root” (from which the arm150 extends); and any combination thereof.

Because of repeated attachments and dis-attachments of the refill 30 toand from the handle 20, there is an inevitable wear at the interface ofthe coupling pin 230 and the coupling surfaces 153, particularly in anenvironment likely containing abrasive material such as toothpasteslurry. It is therefore beneficial to have the coupling pin 230 (whichis part of the handle 20) made of steel or other hard-surface,wear-resilient materials (e.g., steel, ceramics, surface-reinforcedplastic, and various suitable surface-coated materials), and thecoupling surfaces 153 (which are part of the refill 30) made of plastic.Such an arrangement beneficially meets the requirements of functionalityand the respective expected longevities of the handle 20 and the refill30.

The clamp portion 155 of each of the first and second coupling surfaces153 can be structured and configured to abut a side surface of thecoupling pin 230 such that substantially an entire surface of the clampportion 155 is in contact with the side surface of the coupling pin 230when the refill 30 is attached to the handle 20. In other words, therespective surfaces of the pin 230 and the clamp portions 155 can besized and shaped such that virtually the entire clamp portion 155 ofeach of the first and second coupling surfaces 153 a, 153 b is incontact with the corresponding surface of the pin 230, to provide asecure engagement between the handle 20 and the refill 30 when therefill 30 is attached to the handle 20.

The pin 230 may have any suitable shape, e.g., cylindrical, prismatic,conical, and others, although the cylindrical or conical shape may bepreferred. Correspondingly, the clamp portions 155 of the couplingsurfaces 153 can also be profiled to have a circular or semi-circularshape, wherein a diameter of the pin 230 is substantially equal to anequivalent diameter of the clamp portion 155. In such an arrangement,the entire surface of the clamp portion 155 will be in contact with theside surface of the coupling pin 230, as is described above. Since thetwo mutually opposite coupling surfaces 153, contacting the coupling pin230, may have a space therebetween and thus may not comprise a perfectcircle, the term “equivalent diameter,” as used herein, refers to animaginary or theoretical diameter of that the clamp portions 155 basedon radii of their respective curvatures.

The refill 30, and the coupling mechanism 100, can be structured tocomprise a coupling insert 110 disposed inside the tubular portion 33 ofthe refill 30 and fit-pressed thereto, e.g., by utilizing a plurality ofpress-fit segments 111. One exemplary embodiment of such press-fitsegments, comprising protrusions 111 from the insert's outer surface, isschematically shown in FIG. 6. In a further embodiment, the protrusions111 can have corresponding segments, e.g., corresponding depressions(not shown) disposed on the inner side of the tubular portion 33 of therefill 30. The press-fit segments can be distributed equidistantly,e.g., at 60 degrees, from one another around the interface perimeterbetween the tubular portion 33 and the insert 110.

As is best shown in FIGS. 9 and 8A, the insert 110 can have a frontsegment 120 comprising a lower section 121, an upper section 123, and amiddle section 122 intermediate the lower section 121 and the uppersection 123. The lower section 121 is separated from the middle section122 by a first semi-circular space 124, and the middle section 122 isseparated from the upper section 123 by a second semi-circular space125. As used herein, the front segment 120 of the insert 110 is theinsert's semi-circular portion that includes both cantilevered arms 150a, 150 b in their entirety, from the first end 151 a of the first arm150 a to the first end 151 b of the second arm 150 b. In plan view ofFIG. 8A, the front segment 120 is outlined by an included angle α3,formed in a plan-view of the insert 110 between two planes PA and PBparallel to a longitudinal axis A, which angle can be from about 70degrees to about 200 degrees, from about 80 degrees to about 190degrees, and from about 90 degrees to about 180 degrees.

The lower section 121 of the coupling insert 110 may comprise an annularflange 126 extending in a direction substantially perpendicular to thelongitudinal axis A and comprising an inner perimeter 126 a and an outerperimeter 126 b. When the refill 30, having the coupling insert 110incorporated therein, is securely attached to the handle 20, the annularflange 126 can be positioned adjacent to the handle 20, FIG. 4. Theflange 126 may beneficially include, adjacent to its inner perimeter 126a, a recess 127 sized and shaped to provide a space for the rib 240 andthe pin 230 of the coupling stem 200 when the refill 30 is being axiallyattached to the handle 20.

The middle section 122 includes the pair of mutually oppositecantilevered arms 150, previously described. The cantilevered arms 150are positioned such that they can resiliently move, as previouslydescribed, relative to the lower section 121 and the upper section 123of the coupling insert 110. The upper section 123 may include the groove128, previously described, for engaging the upper end 242 of the rib 240outwardly projecting and longitudinally extending from the coupling stem200, to restrict radial and/or axial movement of the refill 30 relativeto the handle 20 when the refill 30 is being axially attached to thehandle 20.

To ensure a secure connection between the refill 30 and the handle 20,the outer walls 210 of the coupling stem 200 and the refill walls can beconstructed to form, in combination, a plurality of press-fit segments250 wherein respective opposite faces of the outer walls 210 and therefill walls frictionally engage one another when the refill 30 isattached to the handle 20. Press-fit segments 250, frictionally unitingthe refill 30 and the stem 200, can be provided at any suitablelocation, e.g., adjacent to the free end 220 of the coupling stem 200and/or adjacent to an end opposite to the free end 220 of the couplingstem 200. As is shown in FIG. 10, e.g., the plurality of press-fitsegments 250 may comprise at least three (upper) press-fit segments 251,252, 253 adjacent to the free end 220 of the coupling stem 200. Theplurality of press-fit segments 250 may further include at least three(lower) press-fit segments 254, 255, 256 adjacent to the end opposite tothe free end 220 of the coupling stem 200. The (lower) press-fitsegments 254, 255, 256 can beneficially comprise portions of the innerperimeter 126 a of the flange 126 of the coupling insert's lower section121, as is best shown in FIG. 11.

In another embodiment, schematically shown in FIGS. 13 and 14, thecoupling insert 110 comprises a tolerance-compensation spring 170extending upright in a general direction substantially parallel to thelongitudinal axis A. The tolerance-compensation spring 170 can bebeneficially formed (e.g., molded) is an integral part of the couplinginsert. The tolerance-compensation spring 170 has a free end and aninner surface 171. The tolerance-compensation spring 170 is structuredand configured so that when the refill 30 is attached to the handle 20,at least an upper portion of the tolerance-compensation spring's innersurface 171 (that is, the inner surface's portion adjacent to the freeend of the tolerance-compensation spring 170) resiliently abuts theadjacent surface of the coupling stem 200, thereby providing africtional fit-press connection therebetween. Although a singletolerance-compensation spring 170 is illustrated herein, embodimentscomprising two or more tolerance-compensation springs of this or asimilar construction are contemplated by this disclosure.

In a further embodiment, each of the cantilevered arms 150 may comprisea curved portion 160 and a fin 160 a, 160 b integrally formed with thecurved portion 160 (FIG. 9). The fin can be generally verticallyoriented. The fin includes the coupling surface 153, previouslydescribed. The curved portion 160 has a curvature length L measured in acircumferential direction, a curvature height H measured at the highest(tallest) portion of the curved portion 160 in a direction generallyperpendicular to the curvature length L, and a curvature thickness Wmeasured in a direction generally perpendicular to the curvature heightH, wherein the curvature length is greater than the curvature height Hand the curvature height H is greater than the curvature thickness W.Given a certain plastic material of the cantilevered arms 150, e.g.,polyoxymethylene (POM) or reinforced POM, having beneficial physicalproperties, these dimensions L, W, and H, can be carefully chosen tofacilitate the elastic deformation of the cantilevered arms 150. Aspreviously described, such deformation may include at least one of aradial-bending elastic deformation, i.e., an outward resilient“unbending” movement of the arms 150 away from the longitudinal axis A;an axial-bending elastic deformation, i.e., a resilient movement of thearms 150 substantially along the longitudinal axis A (i.e., up-and-downmovement); a torsion-twisting elastic deformation, i.e., a resilienttorque movement of the cantilevered arms 150 wherein the couplingsurface 153 rotates relative to the arm's fixed end (or “root”) 151,from which the arm 150 extends; and any combination thereof.

The vertical fin 160 a, 160 b has a fin height H1. As is shown inseveral Figures, the fin height H1 can (but does not have to) be greaterthan the curvature height H. In one exemplary non-limiting embodiment,the curvature length can be from about 4 mm to about 10 mm, from about4.5 mm to about 9 mm, and from about 5 mm to about 8 mm. The curvatureheight can be from about 2 mm to about 8 mm, from about 2.5 mm to about6.5 mm, and from about 3 to about 5 mm. The curvature thickness can befrom about 0.5 mm to about 2 mm, from about 0.7 mm to about 1.8 mm, andfrom about 0.9 mm to about 1.6 mm. The fin height can be from about 3 mmto about 12 mm, from about 5 mm to about 10 mm, and from about 6 mm toabout 9 mm.

The refill 30 may include a motion transmitter 300 therein. In oneembodiment, the motion transmitter 300 terminates with a first magneticcoupling element 310, while a drive mechanism of the handle 20terminates with a second magnetic coupling element 410, FIG. 7. Then,the first magnetic coupling element 310 and the second magnetic couplingelement 410 can be structured and configured to form a secure magneticconnection therebetween when the refill 30 is attached to the handle 20,so that the movement of the handle's drive mechanism is effectivelytransmitted to the refill's motion transmitter 300. Such magneticcoupling elements may include permanent magnet or magnets and/or amagnetizable element or elements, as is described in the commonlyassigned U.S. Pat. No. 8,631,532, the disclosure of which incorporatedherein by reference.

The drive mechanism of the handle 20 can be structured and configuredfor a linear oscillatory movement substantially along the longitudinalaxis A, while the brush head 31 can be structured and configured for arotational oscillatory motion around a rotation axis X extendingsubstantially perpendicular to the longitudinal axis A, a lateraloscillatory motion around an axis extending substantially parallel tothe longitudinal axis A, or any other type of movement, including alinear oscillatory movement, or vibratory action, and other movementpatterns, as is known in the art.

While particular embodiments have been illustrated and described herein,various other changes and modifications may be made without departingfrom the spirit and scope of the invention. Moreover, although variousaspects of the invention have been described herein, such aspects neednot be utilized in combination. It is therefore intended to cover in theappended claims all such changes and modifications that are within thescope of the invention.

The terms “substantially,” “essentially,” “about,” “approximately,” andthe like, as may be used herein, represent the inherent degree ofuncertainty that may be attributed to any quantitative comparison,value, measurement, or other representation, as one skilled in the artwill readily appreciate. These terms also represent the degree by whicha quantitative representation may vary from a stated reference withoutresulting in a change in the basic function of the subject matter atissue. Further, the dimensions and values disclosed herein, whether ornot preceded by the terms “substantially,” “essentially,” “about,”“approximately,” and the like, are not to be understood as beingstrictly limited to the exact numerical values recited. Instead, unlessotherwise specified, each such dimension is intended to mean both therecited value and a functionally equivalent range surrounding thatvalue. For example, values disclosed as “5 mm” and “70 degrees” areintended to mean “about 5 mm” and “about 70 degrees” respectively.

The disclosure of every document cited herein, including anycross-referenced or related patent or application and any patentapplication or patent to which this application claims priority orbenefit thereof, is hereby incorporated herein by reference in itsentirety unless expressly excluded or otherwise limited. The citation ofany document is not an admission that it is prior art with respect toany invention disclosed or claimed herein—or that it alone, or in anycombination with any other reference or references, teaches, suggests,or discloses any such invention. Further, to the extent that any meaningor definition of a term in this document conflicts with any meaning ordefinition of the same or similar term in a document incorporated hereinby reference, the meaning or definition assigned to or contextuallyimplied by that term in this document shall govern.

1. A refill for an electric toothbrush having a longitudinal axis, therefill having a movable brush head and being structured and configuredto be attached to a handle of the electric toothbrush, the refillcomprising a generally tubular structure formed by refill walls definingan interior space for accepting thereinto a coupling stem of the handle,wherein the refill includes a motion transmitter functionally connectedto the brush head for driving the brush head, wherein the refillincludes a coupling insert comprising a pair of mutually oppositecantilevered arms disposed in the interior space of the refill andadjacent to the refill walls, wherein each of the arms extends in acircular or semicircular direction around the longitudinal axis and in aplane substantially perpendicular to the longitudinal axis, wherein eachof the arms is resiliently deformable relative to the root andterminates with a coupling surface structured and configured to engage acoupling pin extending from the coupling stem of the handle for secureand disengageable connection therewith.
 2. The refill of claim 1,wherein the coupling surfaces of the cantilevered arms are structuredand configured to engage the coupling pin that extends from the couplingstem of the handle in a direction substantially perpendicular to thelongitudinal axis.
 3. The refill of claim 1, wherein the couplingsurfaces of the cantilevered arms are structured and configured toengage the coupling pin that extends from the coupling stem intermediatea lower end and an upper end of a rib extending from the coupling stemin a direction substantially perpendicular to the longitudinal axis andlengthwise oriented substantially parallel to the longitudinal axis. 4.The refill of claim 1, wherein the pair of mutually oppositecantilevered arms terminating with coupling surfaces comprises a firstcantilevered arm terminating with a first coupling surface and a secondcantilevered arm terminating with a second coupling surface opposite toand facing the first coupling surface, and wherein the first and secondcoupling surfaces are structured and configured to simultaneouslyembrace the coupling pin at opposite sides thereof when the refill isattached to the handle.
 5. The refill of claim 4, wherein the firstcoupling surface and the second coupling surface are structured andconfigured to slidably and resiliently engage the coupling pin when therefill is being axially attached to the handle.
 6. The refill of claim5, wherein each of the first and second coupling surfaces comprises aslide portion and a clamp portion adjacent to the slide portion.
 7. Therefill of claim 6, wherein each of the slide portions includes achamfer.
 8. The refill of claim 6, wherein the slide portion of each ofthe first and second coupling surfaces is substantially parallel to thelongitudinal axis.
 9. The refill of claim 6, wherein the slide portionof each of the first and second coupling surfaces is angled relative tothe longitudinal axis, and wherein an included angle between the slideportions is from about 0.1 degree to about 20 degrees.
 10. The refill ofclaim 6, wherein the clamp portion of each of the first and secondcoupling surfaces is structured and configured to abut a side surface ofthe coupling pin such that substantially an entire surface of the clampportion is in contact with the side surface of the coupling pin when therefill is attached to the handle.
 11. The refill of claim 10, whereinthe clamp portion of each of the first and second coupling surfaces iscircular, having a diameter substantially equal to an equivalentdiameter of the coupling pin.
 12. The refill of claim 11, wherein thediameter of the coupling surface is from about 0.8 mm to about 6 mm. 13.The refill of claim 12, wherein a distance between the mutually oppositeslide portions of the first and second coupling surfaces is from about0.4 mm to about 5 mm.
 14. The refill of claim 3, wherein the refillcomprises a groove structured and configured to engage the upper end ofthe rib extending from the coupling stem, thereby restricting axialmovement of the refill relative to the handle when the refill is beingaxially attached to the handle.
 15. The refill of claim 1, wherein therefill includes a coupling insert having a front segment comprising anupper section, a lower section, and a middle section between the upperand lower sections, wherein the lower section is separated from themiddle section by a first semi-circular space and the middle section isseparated from the upper section by a second semi-circular space,wherein the lower section is adjacent to the handle when the refill isattached thereto, wherein the middle section comprises the pair ofmutually opposite cantilevered arms, and wherein the upper sectioncomprises a groove structured and configured to engage an upper end of arib longitudinally extending from the neck of the handle therebyrestricting axial movement of the refill relative to the handle when therefill is being axially attached to the handle.
 16. The refill of claim15, wherein the mutually opposite cantilevered arms are structured andconfigured to resiliently move relative to the lower section and theupper section of the insert.
 17. The refill of claim 16, wherein aresilient movement of the cantilevered arms relative to the lowersection and the upper section of the insert includes a movement selectedfrom the group consisting of a radial-bending movement, an axial-bendingmovement, a torsion-twisting movement, and any combination thereof. 18.The refill of claim 1, wherein the refill walls are structured andconfigured to form, in combination with the outer walls of the couplingstem, a plurality of press-fit segments wherein opposite faces of saidsegments frictionally engage one another when the refill is attached tothe handle.
 19. The refill of claim 18, wherein the press-fit portionsare provided at longitudinally opposite ends of the coupling device. 20.The refill of claim 19, wherein there are at least three press-fitsegments at each of the opposite ends of the coupling device, thesegments being substantially equidistantly spaced from one another. 21.The refill of claim 1, wherein the motion transmitter of the refillterminates with a first coupling element connected to the motiontransmitter and structured and configured for establishing an operativeconnection with a second coupling element provided in the handle. 22.The refill of claim 21, wherein the first coupling element comprises afirst magnetic element selected from the group consisting of a permanentmagnet, a magnetizable element, or any combination thereof, suitable forestablishing a magnetic connection with a second magnetic couplingelement provided in the handle.
 23. The refill of claim 1, wherein themotion transmitter is structured and configured for linear oscillatorymovement substantially along the longitudinal axis.
 24. The refill ofclaim 15, wherein the coupling insert comprises at least onetolerance-compensation spring outwardly extending in a general directionof the longitudinal axis, wherein the tolerance-compensation spring hasa free end and is structured and configured so that when the refill isattached to the handle, at least a portion of the tolerance-compensationspring adjacent to its free end resiliently biases the coupling insertagainst the coupling stem, thereby providing a frictional press-fitcontact therebetween.
 25. A refill for an electric toothbrush having alongitudinal axis, the refill having a movable brush head and beingstructured and configured to be attached to a handle of the electrictoothbrush, the refill comprising a generally tubular structure formedby refill walls defining an interior space for accepting thereinto acoupling stem of the handle, wherein the refill includes a motiontransmitter functionally connected to the brush head for driving thebrush head wherein the refill comprises a coupling insert including apair of mutually opposite cantilevered arms disposed in the interiorspace of the refill and adjacent to the refill walls, wherein each ofthe arms extends from a root in a circular or semicircular directionaround the longitudinal axis, wherein each of the arms is resilientlydeformable relative to the root and terminates with a coupling surfacestructured and configured to engage a coupling pin extending from thecoupling stem of the handle for secure and disengageable connectiontherewith, and wherein the root, the arm, and the coupling surface aredisposed in a plane substantially perpendicular to the longitudinalaxis.